1. Field Of The Invention
The invention generally relates to hard disk drives and in particular to an improved slider apparatus for use in a hard disk drive.
2. Description Of Related Art
A typical hard disk drive system includes a recording head having magnetic recording transducer mounted at the end of an actuator arm assembly. The actuator arm assembly is adapted to position the magnetic recording transducer over a spinning hard disk to allow magnetic reading and writing operations to be performed on portions of the spinning disk. To facilitate proper positioning of the magnetic recording transducer over the hard disk, the transducer is mounted within a slider positioned at an extreme distal end of the actuator arm assembly. In operation, the slider slides along the spinning hard disk either in direct contact with the disk or at a slight height above the disk.
A primary goal of hard disk drives is to provide a maximum recording density in the hard disk. It has been found that the recording density that can be achieved using a magnetic recording transducer depends on the distance between the recording media of the hard disk and the magnetic recording transducer. From a recording density standpoint, the transducer is ideally maintained in direct contact with the recording media of the hard disk. However, the hard disk typically spins at about 4,000 RPM and continuous direct contact between the slider and the recording media causes unacceptable wear in both the recording media and the slider. Wear occurring in the recording media can result in a loss of data. Wear occurring in the slider can ultimately result in a complete failure of the recording transducer requiring replacement of the slider, as well as loss of data.
To prevent undue wear of the recording media and the slider while still maintaining a high recording density, a bottom surface of the slider is typically configured as an air bearing surface (ABS). High speed rotation of the disk causes a stream of air to flow along the surface of the disk. The ABS of the slider interacts with the flow of air causing the slider to float above the hard disk surface. Hence, while the disk is spinning and the slider is positioned adjacent to the disk, the slider is elevated slightly above the disk substantially eliminating any wear to either the disk or the slider. To achieve adequate lift, the ABS may include a slight ramp formed along a leading edge of the bottom surface of the slider and a pair of rails formed along side edges of the bottom surface of the slider. The ramp allows a portion of air to be drawn underneath the slider. The rails provide a longitudinal conduit for air flow which extends along the entire bottom surface to a rear edge of the slider.
Although the above-described ABS slider design has been effective in preventing wear of the slider and the recording media, optimal recording densities have not been achieved due to separation between the recording media and the magnetic recording transducer of the slider. To achieve higher linear recording densities, the separation between the magnetic recording transducer and the magnetic recording media should be decreased. For the past several decades, attempts to decrease the separation distance has primarily involved improvements to the surface smoothness and flatness of the recording media and improvements to air bearing designs that provide lower and lower recording head/recording media distances. Heretofore, distances of less than two micro-inches have not been achieved.
Although an ABS design maintains the slider elevated above the disk during normal operation, the slider actually contacts the disk during start up and shut down of the disk drive. In such circumstances, the slider and recording media contact in a dedicated landing zone wherein no data is recorded. Because of landing zone contact, the slider and the disk are in contact up to 0.1% of the typical operation time of the hard drive. Hence, a certain amount of wear of the slider is inevitable, even for the ABS design.
Some head designs provide for full contact recording wherein the head and disk are in contact 100% of the operation time of the device. Although high recording densities can be achieved using a full contact approach, considerable head or media wear can occur. In particular, head/disk durability must be increased one thousand fold over that of a conventional ABS system for the full contact approach to have an equivalent durability to that of the air bearing system, wherein the head is in contact with the disk less than 0.1% of the operational time. The thousand fold increase in durability may be difficult or impossible to achieve, resulting in increased wear over the non-contact ABS system resulting in shorter lifetimes for the operational disk.